U.S. patent number 8,513,682 [Application Number 12/808,953] was granted by the patent office on 2013-08-20 for optoelectronic component and production method for an optoelectronic component.
This patent grant is currently assigned to OSRAM Opto Semiconductors GmbH. The grantee listed for this patent is Bert Braune, Matthias Rebhan, Norbert Stath, Walter Wegleiter, Karl Weidner, Hans Wulkesch. Invention is credited to Bert Braune, Matthias Rebhan, Norbert Stath, Walter Wegleiter, Karl Weidner, Hans Wulkesch.
United States Patent |
8,513,682 |
Wegleiter , et al. |
August 20, 2013 |
**Please see images for:
( Certificate of Correction ) ** |
Optoelectronic component and production method for an
optoelectronic component
Abstract
An optoelectronic component includes a carrier element. At least
two elements are arranged in an adjacent fashion on a first side of
the carrier element. Each element has at least one optically active
region for generating the electromagnetic radiation. The
optoelectronic component has an electrically insulating protective
layer arranged at least in part on a surface of the at least two
adjacent elements which lies opposite the first side. The
protective layer, at least in a first region arranged between the
at least two adjacent elements, at least predominantly prevents a
transmission of the electromagnetic radiation generated by the
optically active regions.
Inventors: |
Wegleiter; Walter (Nittendorf,
DE), Stath; Norbert (Regensburg, DE),
Braune; Bert (Wenzenbach, DE), Weidner; Karl
(Munich, DE), Rebhan; Matthias (Riemerling,
DE), Wulkesch; Hans (Munich, DE) |
Applicant: |
Name |
City |
State |
Country |
Type |
Wegleiter; Walter
Stath; Norbert
Braune; Bert
Weidner; Karl
Rebhan; Matthias
Wulkesch; Hans |
Nittendorf
Regensburg
Wenzenbach
Munich
Riemerling
Munich |
N/A
N/A
N/A
N/A
N/A
N/A |
DE
DE
DE
DE
DE
DE |
|
|
Assignee: |
OSRAM Opto Semiconductors GmbH
(Regensburg, DE)
|
Family
ID: |
40690073 |
Appl.
No.: |
12/808,953 |
Filed: |
December 11, 2008 |
PCT
Filed: |
December 11, 2008 |
PCT No.: |
PCT/DE2008/002067 |
371(c)(1),(2),(4) Date: |
July 20, 2010 |
PCT
Pub. No.: |
WO2009/079985 |
PCT
Pub. Date: |
July 02, 2009 |
Prior Publication Data
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|
|
Document
Identifier |
Publication Date |
|
US 20100301355 A1 |
Dec 2, 2010 |
|
Foreign Application Priority Data
|
|
|
|
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Dec 21, 2007 [DE] |
|
|
10 2007 062 045 |
Apr 21, 2008 [DE] |
|
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10 2008 019 902 |
|
Current U.S.
Class: |
257/91;
257/E33.07; 438/28 |
Current CPC
Class: |
H01L
51/5284 (20130101); H01L 25/0753 (20130101); H01L
51/52 (20130101); H01L 24/24 (20130101); H01L
2924/12041 (20130101); H01L 33/44 (20130101); H01L
2924/01029 (20130101); H01L 51/5253 (20130101); H01L
2924/12044 (20130101); H01L 33/46 (20130101); H01L
2224/73267 (20130101); H01L 33/60 (20130101); H01L
2924/12041 (20130101); H01L 2924/00 (20130101); H01L
2924/12044 (20130101); H01L 2924/00 (20130101) |
Current International
Class: |
H01L
33/00 (20100101) |
Field of
Search: |
;257/91,E33.067,E33.07,88,E33.068,99 ;438/28,29 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1456025 |
|
Nov 2003 |
|
CN |
|
103 39 985 |
|
Mar 2005 |
|
DE |
|
10339985 |
|
Mar 2005 |
|
DE |
|
10 2004 050 371 |
|
Apr 2006 |
|
DE |
|
10 2006 015 115 |
|
Oct 2007 |
|
DE |
|
10 2007 011 123 |
|
Sep 2008 |
|
DE |
|
EP 0 905 797 |
|
Mar 1999 |
|
EP |
|
55-077876 |
|
May 1980 |
|
JP |
|
60-253286 |
|
Dec 1985 |
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JP |
|
60253286 |
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Dec 1985 |
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JP |
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62-199073 |
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Sep 1987 |
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JP |
|
64-071187 |
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Mar 1989 |
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JP |
|
64071187 |
|
Mar 1989 |
|
JP |
|
11-238915 |
|
Aug 1999 |
|
JP |
|
2006-086191 |
|
Mar 2006 |
|
JP |
|
200301972 |
|
Jul 2003 |
|
TW |
|
WO 2007/025521 |
|
May 1980 |
|
WO |
|
WO 97/48138 |
|
Dec 1997 |
|
WO |
|
WO 02/13281 |
|
Feb 2002 |
|
WO |
|
WO 03/012884 |
|
Feb 2003 |
|
WO |
|
WO 2006/044894 |
|
Apr 2006 |
|
WO |
|
Other References
Schnitzer, I., et al., "30% External Quantum Efficiency from
Surface Textured, Thin-Film Light-Emitting Diodes," Applied Physics
Letters, Oct. 18, 1993, 3 pages, American Institute of Physics.
cited by applicant.
|
Primary Examiner: Maldonado; Julio J
Assistant Examiner: Shook; Daniel
Attorney, Agent or Firm: Slater & Matsil, L.L.P.
Claims
The invention claimed is:
1. An optoelectronic component, comprising: a carrier element; a
plurality of LED-chips arranged in an adjacent fashion on a first
side of the carrier element, each of the LED-chips having one
single optically active region for generating electromagnetic
radiation; and an electrically insulating protective layer arranged
at least in part on a surface of the LED-chips that lies opposite
the first side, wherein the protective layer, at least in a first
region arranged between the LED-chips, at least predominantly
prevents a transmission of the electromagnetic radiation generated
by the one single optically active region and wherein the
electrically insulating protective layer absorbs the
electromagnetic radiation in the first region.
2. The optoelectronic component as claimed in claim 1, wherein the
electrically insulating protective layer is interrupted in the
first region.
3. The optoelectronic component as claimed in claim 1, wherein a
depression is arranged between the LED-chips.
4. The optoelectronic component as claimed in claim 3, wherein the
depression extends over an entire height of the LED-chips.
5. The optoelectronic component as claimed in claim 4, further
comprising a reflecting element arranged in the first region, the
reflecting element extending at least partly into the
depression.
6. The optoelectronic component as claimed in claim 3, wherein the
electrically insulating protective layer penetrates at least partly
into the depression in a direction towards the carrier element.
7. The optoelectronic component as claimed in claim 1, wherein the
LED-chips comprise a plurality of elements arranged in a matrix
structure.
8. The optoelectronic component as claimed in claim 1, wherein at
least parts of the protective layer are embodied as a colored
foil.
9. The optoelectronic component as claimed in claim 8, wherein the
colored foil comprises a black foil.
10. The optoelectronic component as claimed in claim 1, wherein the
protective layer, in the first region, absorbs more than 90 percent
of the electromagnetic radiation.
11. An optoelectronic component, comprising: a carrier element; a
plurality of LED-chips arranged in an adjacent fashion on a first
side of the carrier element, each of the LED-chips having one
single optically active region for generating electromagnetic
radiation; an electrically insulating protective layer arranged at
least in part on a surface of the LED-chips that lies opposite the
first side, wherein the protective layer, at least in a first
region arranged between the LED-chips, at least predominantly
prevents a transmission of the electromagnetic radiation generated
by the one single optically active region of each LED-chip; and an
electrically conductive connection layer for electrically
connecting each of the optically active regions, the electrically
conductive connection layer arranged on at least one second region
of the protective layer.
12. The optoelectronic component as claimed in claim 11, wherein
the protective layer, in the at least one second region, is at
least predominantly opaque to the electromagnetic radiation
generated by the optically active regions.
13. The optoelectronic component as claimed in claim 11, further
comprising a photoluminescent conversion element arranged in at
least one third region of the protective layer, the conversion
element absorbing electromagnetic radiation having a first
wavelength and emitting electromagnetic radiation having a second
wavelength.
14. A method for producing an optoelectronic component, the method
comprising: arranging a plurality of LED-chips adjacent to one
another on a first side of a carrier element, each LED-chip having
one single optically active region for generating an
electromagnetic radiation, and applying an electrically insulating
protective layer to a surface of the LED-chips that lies opposite
the first side, wherein the protective layer, in at least one first
region arranged between the LED-chips, at least predominantly
prevents a transmission of the electromagnetic radiation generated
by the optically active regions and wherein the electrically
insulating protective layer absorbs the electromagnetic radiation
in the first region.
15. The method as claimed in claim 14, further comprising: creating
at least one cutout in the protective layer, applying an
electrically conductive connection layer on the protective layer,
and producing an electrical contact between the connection layer
and at least two adjacent elements in a region of the at least one
cutout.
16. The method as claimed in claim 15, wherein a depression is
formed between the LED-chips.
17. The method as claimed in claim 16, further comprising forming a
reflecting element in the first region, the reflecting element
extending at least partly into the depression.
18. The method as claimed in claim 14, wherein a depression is
formed between the LED-chips.
19. The method as claimed in claim 14, further comprising forming a
photoluminescent conversion element in at least a third region of
the protective layer, the conversion element receiving
electromagnetic radiation having a first wavelength and emitting
electromagnetic radiation having a second wavelength.
20. The method as claimed in claim 14, wherein the protective
layer, in the first region, absorbs more than 90 percent of the
electromagnetic radiation.
Description
This patent application is a national phase filing under section
371 of PCT/DE2008/002067, filed Dec. 11, 2008, which claims the
priority of German patent applications 10 2007 062 045.6, filed
Dec. 21, 2007 and 10 2008 019 902.8, filed Apr. 21, 2008, each of
which is incorporated herein by reference in its entirety.
TECHNICAL FIELD
The invention relates to an optoelectronic component comprising a
carrier element and at least two elements arranged adjacent to one
another on a first side of the carrier element and each having at
least one optically active region for generating electromagnetic
radiation.
BACKGROUND
Optoelectronic components comprising two or more elements arranged
in an adjacent fashion for generating electromagnetic radiation are
known. In the lighting field, in particular, where comparatively
high energy densities of emitted electromagnetic radiation are
intended to be achieved, a multiplicity of luminous elements
arranged on a common carrier element is often used.
In some areas of application, for example in the case of active
matrix displays or else in motor vehicle lighting technology, the
spurious luminescence of adjacent elements (also called crosstalk)
and/or optical waveguide effects are intended to be minimized.
Spurious luminescence of adjacent elements leads to a reduction of
contrast, which may be disadvantageous for these applications. By
way of example, for lighting units of a motor vehicle headlight, a
sharp demarcation of those elements which are assigned to a
low-beam light and those elements which are assigned to a high-beam
light operating mode is required.
SUMMARY
In one aspect the present invention provides an optoelectronic
component of the type mentioned above in which spurious
luminescence of adjacent elements, each having at least one
optically active region for generating electromagnetic radiation,
is prevented or at least greatly reduced. Further aspects specify a
production method which allows such an optoelectronic component to
be produced in a simple manner.
An optoelectronic component according to the invention has an
electrically insulating protective layer arranged at least in part
on a surface of the at least two adjacent elements which lies
opposite the first side, wherein the protective layer, at least in
a first region arranged between the at least two adjacent elements
at least predominantly prevents a transmission of the
electromagnetic radiation which can be generated by the optically
active regions.
By using an electrically insulating protective layer which at least
predominantly prevents a transmission of the electromagnetic
radiation which can be generated, it is possible for spurious
luminescence of adjacent elements to be substantially reduced or
even avoided.
In accordance with one advantageous configuration, the electrically
insulating protective layer is interrupted in the first region. In
accordance with a further advantageous configuration, the
electrically insulating protective layer absorbs the
electromagnetic radiation in the first region, such that said
protective layer is opaque to the electromagnetic radiation in the
first region. If the protective layer is interrupted in the first
region or if it absorbs the electromagnetic radiation, no or only a
significantly reduced transmission from the first to the second
optically active region takes place by means of wave guiding in the
protective layer.
In accordance with one advantageous configuration, a depression is
arranged between the at least two adjacent elements. In accordance
with a further advantageous configuration, the depression extends
over the entire height of the at least two elements. The depression
between the first and second optically active elements reduces an
optical coupling of the two elements arranged in an adjacent
fashion, particularly if it extends over the entire height.
In accordance with a further advantageous configuration, a
reflecting element is arranged in the first region, said reflecting
element extending at least partly into the depression. In
accordance with a further configuration, the reflecting element
completely fills the depression in a direction towards the carrier
element. The reflecting element reflects the radiation generated by
the respective optically active region, such that an excitation of
the respective other optically active region is avoided,
particularly if the reflecting element completely fills the
depression.
In accordance with a further configuration, the reflecting element
comprises a galvanically applied metal layer. In accordance with a
further configuration, the galvanically applied metal layer is
embodied as a connection element, for example as a copper pillar,
for electrically connecting at least one of the optically active
regions. This has the advantage that the reflecting element can be
produced in a simple manner together with other production steps,
for instance that of applying a connection contact.
In accordance with a further advantageous configuration, the
protective layer penetrates at least partly into the depression in
a direction towards the carrier element. A diaphragm effect of the
protective layer is achieved by virtue of the protective layer
penetrating into the depression.
In accordance with a further advantageous configuration, the
protective layer completely fills the depression in a direction
towards the carrier element. This brings about an improved optical
separation of the adjacent elements.
In accordance with a further advantageous configuration, an
electrically conductive connection layer for feeding an electrical
voltage to the at least two optically active regions is arranged on
at least one second region of the protective layer. The electrical
connection of the at least two optically active regions can be
simplified by virtue of an electrically conductive connection layer
being arranged on the protective layer.
In accordance with a further advantageous configuration, the
protective layer, in the second region, is at least predominantly
opaque to the electromagnetic radiation generated by the optically
active regions. Such a configuration makes it possible to reduce
undesired reflections from the connection layer back to the
optically active regions.
In accordance with a further advantageous configuration, at least
one electrically conductive contact area for electrically
connecting at least one of the optically active regions is arranged
on the carrier element. The use of an electrically conductive
contact area enables the electrical contact-connection of the
optically active regions to be simplified further.
In accordance with a further advantageous configuration, a
photoluminescent conversion layer is arranged in at least one third
region of the protective layer, said conversion layer absorbing
electromagnetic radiation having a first wavelength and emitting
electromagnetic radiation having a second wavelength. Through the
use of a photoluminescent conversion layer in a third region of the
protective layer, the radiation profile of the at least two
adjacent elements is adapted in accordance with requirements.
In accordance with a further advantageous configuration, the at
least two adjacent elements are in each case embodied as a
luminescence diode structure, in particular as an LED or OLED
structure. The use of LED or OLED structures permits simple and
efficient generation of electromagnetic radiation by the at least
two adjacent elements.
In accordance with a further advantageous configuration, the
luminescence diodes are embodied as thin-film light emitting diode
chips. By using substrateless semiconductor layer stacks, it is
possible to manufacture particularly thin optoelectronic
components.
In accordance with a further advantageous configuration, the at
least two adjacent elements are in each case embodied as a surface
emitter. The use of a surface emitter allows particularly
advantageous beam formation.
In accordance with a further advantageous configuration, a
plurality of elements each having at least one optically active
region are arranged on the first side of the carrier element,
wherein the plurality of elements forms a matrix structure. Through
the use of a plurality of elements in a matrix structure, diverse
luminous patterns and display functions can be produced by the
component.
In accordance with a further advantageous configuration, at least
parts of the protective layer are embodied as a colored, in
particular black, foil. The use of colored foils allows the
protective layer to be produced and applied in a particularly
simple manner.
In accordance with a further advantageous configuration, the
colored foil comprises a polymer, in particular a silicone. Polymer
foils can be produced in a large number of colors with desired
properties. Silicone material has a high durability under the
action of short-wave electromagnetic radiation and is therefore
suitable particularly in the case of use with optically active
regions which emit electromagnetic radiation in the blue or
ultraviolet range.
In accordance with a further advantageous configuration, the foil
has at least one cutout in each case in the region of the at least
two optically active regions. By virtue of the cutout in the region
of the at least two optically active regions, the foil acts as a
diaphragm element that can be produced in a simple manner for an
underlying radiation area.
A production method for an optoelectronic component according to
the invention is disclosed. At least two elements, each having at
least one optically active region for generating an electromagnetic
radiation, are arranged in adjacent fashion on a first side of a
carrier element. An electrically insulating protective layer is
applied to a surface of the at least two adjacent elements which
lies opposite the first side. The protective layer, in at least one
first region arranged between the at least two adjacent elements,
at least predominantly prevents a transmission of the
electromagnetic radiation which can be generated by the optically
active regions.
By means of the method steps mentioned above, an optoelectronic
component comprising at least two adjacent elements is produced in
which spurious luminescence of the adjacent elements is at least
predominantly prevented.
In accordance with one advantageous configuration, arranging the at
least two adjacent elements additionally comprises producing a
first electrical contact between contact areas of the carrier
element and the at least two adjacent elements. By virtue of
jointly producing a first electrical contact together with
arranging the at least two elements on the carrier element, the
connection of the at least two adjacent elements is simplified.
In accordance with a further advantageous configuration, the method
additionally comprises creating at least one cutout in the
protective layer, applying an electrically conductive connection
layer on the protective layer, and producing a second electrical
contact between the connection layer and the at least two adjacent
elements in the region of the at least one cutout. By virtue of
applying a connection layer and producing a contact in the region
of the cutout, it is possible for the electrical contact-connection
of the at least two adjacent elements to be simplified further.
In accordance with a further advantageous configuration, applying
the electrically insulating protective layer comprises areally
applying a transparent insulation material to the carrier element
with the at least two elements. Areally applying the transparent
insulation material can be carried out particularly simply in terms
of production engineering.
In accordance with one advantageous configuration, the electrically
insulating protective layer is interrupted in the first region.
Technically simple production of the optoelectronic component is
made possible by virtue of the protective layer being interrupted
in the region which serves for optical separation between the two
elements.
In accordance with an alternative configuration, the transparent
insulation material in the at least one first region is colored by
introducing at least one first foreign substance, for example a dye
or a radiation-absorbing or reflecting filler. Coloring an
initially transparent insulation material in the region which
serves for optical separation between the two elements likewise
enables the optoelectronic component to be produced in a
technically simple manner.
In accordance with a further advantageous configuration, the
transparent material is spun onto a carrier material. A
conventional spin-coating method can advantageously be employed for
this purpose.
In accordance with a further advantageous configuration, the
production method additionally comprises forming a conversion
element in at least one third region of the protective layer by
introducing at least one second foreign substance, for example an
organic or inorganic phosphor, into the transparent insulation
material. By introducing a second foreign substance, it is possible
for a conversion element, for example a photoluminescent conversion
layer, to be produced in a particularly simple manner.
In accordance with a further advantageous configuration, applying
the electrically insulating protective layer comprises applying an
insulation material that reflects or absorbs the electromagnetic
radiation to the first side of the carrier element, wherein the
insulation material has in each case at least one cutout in two
third regions assigned to the at least two adjacent elements. As a
result of applying an insulation material having at least two
cutouts in the protective layer, a diaphragm structure is provided
in a technically simple manner. In this case, the cutouts can be
created before or after the application of the insulation material.
The use of a colored foil, in particular, is suitable for this
purpose.
In accordance with a further advantageous configuration, a
depression is shaped between the at least two adjacent elements.
The depression reduces the optical coupling of the adjacent
elements.
In accordance with a further advantageous configuration, a
reflecting element is arranged in the region of the depression. The
reflecting element improves the optical decoupling of the adjacent
elements.
In accordance with a further advantageous configuration, the
reflecting element is deposited galvanically in the depression. In
this way, the reflecting element can be produced particularly
simply in terms of process engineering.
In accordance with a further configuration, the electrically
insulating protective layer is advantageously applied to the first
side by lamination.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is explained in greater detail below on the basis of
exemplary embodiments. In the exemplary embodiments illustrated,
identical reference symbols are used for elements having an
identical or similar function.
In the figures:
FIGS. 1A and 1B show an optoelectronic component in accordance with
one configuration of the invention,
FIG. 2 shows an optoelectronic component in accordance with a
further configuration of the invention,
FIG. 3 shows an optoelectronic component in accordance with a
further configuration of the invention,
FIG. 4 shows an optoelectronic component in accordance with a
further configuration of the invention, and
FIG. 5 shows a flowchart of a method for producing an
optoelectronic component.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
FIG. 1A shows a cross section through an optoelectronic component
1. The optoelectronic component 1 has a carrier element 2 and also
two elements 3a and 3b arranged on the carrier element 2. Each of
the elements 3a and 3b comprises an optically active region 4a and
4b, respectively.
By way of example, the carrier element 2 is a circuit board
material on which are soldered two LED chips as adjacent
radiation-emitting elements 3a and 3b. As an alternative, the
carrier element 2 can also be embodied as a ceramic carrier on
which the elements 3a and 3b are fixedly adhesively bonded. The use
of a ceramic carrier instead of a circuit board material increases
the thermal conductivity of the carrier element 1, in particular,
and is therefore suitable for particularly powerful elements 3a and
3b. The use of a growth substrate, for example of a germanium
wafer, as a carrier element is also possible.
The optically active region 4a and 4b, respectively, can be for
example a region of a semiconductor layer stack in which majority
and minority charge carriers of a semiconductor diode structure
recombine with one another and emit electromagnetic radiation in
the event of an operating voltage being applied.
In one exemplary configuration, the elements 3a and 3b are
thin-film light-emitting diode chips, for example based on a
nitride compound semiconductor material or semiconductor material
systems such as, for example, InGaN or InGaAlP. In this
configuration, a first and a second connection layer are arranged
at least in places between the semiconductor layer sequence and the
carrier element 2. A thin-film light-emitting diode chip is
distinguished by at least one of the following characteristic
features:
a reflective layer is applied or formed at a main area--facing the
carrier element 2, in particular a carrier substrate--of the
radiation-generating semiconductor layer sequence, which is, in
particular, a radiation-generating epitaxial layer sequence, said
reflective layer reflecting at least part of the electromagnetic
radiation 10 generated in the semiconductor layer sequence back
into the latter;
the carrier element 2 is not a growth substrate on which the
semiconductor layer sequence was grown epitaxially, but rather a
separate carrier element 2 which was subsequently fixed to the
semiconductor layer sequence;
the semiconductor layer sequence has a thickness in the range of 20
.mu.m or less, in particular in the range of 10 .mu.m or less;
the semiconductor layer sequence is free of a growth substrate. In
the present case, "free of a growth substrate" means that a growth
substrate used, if appropriate, for growth purposes is removed from
the semiconductor layer sequence or at least greatly thinned. In
particular, it is thinned in such a way that it is not
self-supporting by itself or together with the epitaxial layer
sequence alone. In particular, the remaining residue of the greatly
thinned growth substrate is unsuitable as such for the function of
a growth substrate; and
the semiconductor layer sequence contains at least one
semiconductor layer having at least one area which has an
intermixing structure which ideally leads to an approximately
ergodic distribution of the light in the semiconductor layer
sequence, that is to say that it has an as far as possible
ergodically stochastic scattering behavior.
A basic principle of a thin-film light-emitting diode chip is
described for example in the document I. Schnitzer et al., Appl.
Phys. Lett. 63 (16) Oct. 18, 1993, pages 2174-2176, the disclosure
content of which in this respect is hereby incorporated by
reference. Examples of thin-film light-emitting diode chips are
described in the documents EP 0905797 A2, U.S. Pat. No. 6,111,272,
and WO 02/13281 A1, U.S. Pat. No. 7,109,527, the disclosure content
of which in this respect is hereby likewise incorporated by
reference.
A thin-film light-emitting diode chip is to a good approximation a
Lambertian surface emitter and is therefore well suited, for
example, to application in a headlight, for instance a motor
vehicle headlight.
In the exemplary embodiment in accordance with FIG. 1A, the two
adjacent elements 3a and 3b are at least partly covered with an
electrically insulating protective layer 5. In the exemplary
embodiment, the electrically insulating protective layer 5 consists
of a first region 5a, which is arranged at least in part between
the two adjacent elements 3a and 3b, and also two second regions 5b
on those sides of the elements 3a and 3b which are remote from one
another.
A connection layer 6 is arranged on the second regions 5b, which
connection layer connects a surface of the elements 3a and 3b to
connection contacts 7a and 7b on the carrier element 2.
Furthermore, two contact areas 8a and 8b are arranged on the
carrier element 2, via which contact areas the underside of the
elements 3a and 3b can be supplied with an operating voltage.
The two elements 3a and 3b are separated from one another by a
depression 11, wherein the first region 5a of the protective layer
5 partly projects into the depression 11.
FIG. 1B shows a plan view of the component 1, and the protective
layer 5 can be discerned particularly well in this plan view.
In the exemplary embodiment, the protective layer 5 is formed by a
polymer foil, from which two cutouts 9a are cut out or stamped out
in a region above the elements 3a and 3b. In the switched-on state
of the component, electromagnetic radiation 10, in particular
visible light, e.g. having wavelengths in the range of between 400
and 800 nanometers, emerges through the cutouts 9a in the
protective layer 5.
Furthermore, the protective layer 5 comprises further cutouts 9b
and 9c, through which the connection layer 6 makes electrical
contact with the underlying elements 3a and 3b and the connection
contacts 7a and 7b, respectively. In the exemplary embodiment
illustrated, the connection layer 6 comprises two separate
conductor track elements, which were applied to the component 1 by
means of known photolithographic methods, for example. It goes
without saying that it is also possible to use a common connection
layer for both elements 3a and 3b.
The polymer foil is preferably a colored or black foil which is
wholly or at least predominantly opaque in the wavelength range of
the electromagnetic radiation 10 emitted by the optically active
regions 4a and 4b. Preferably, the protective layer 5, in the first
region 5a, absorbs more than 50 percent of the electromagnetic
radiation 10 impinging on it, particularly preferably more than 75
percent, for example 90 percent, preferably more than 95 percent,
for example 98 percent or more. Electromagnetic radiation 10 which
is emitted at an excessively large emission angle relative to the
vertical with respect to the carrier element 2 is therefore
predominantly absorbed by the polymer foil in the first region 5a
and/or in the second regions 5b of the protective layer 5. This is
illustrated, in particular, by the left-hand arrow on the basis of
the element 3b on the right in FIG. 1A.
As becomes clear from FIGS. 1A and 1B, the protective layer 5
serves a double function. Firstly, it forms diaphragm elements for
the electromagnetic radiation 10 emitted by the optically active
regions 4a and 4b. Furthermore, it insulates the elements 3a and 3b
from the connection layer 6 outside the desired contact regions.
The optoelectronic component 1 in accordance with FIGS. 1A and 1B
can be produced in a particularly simple manner and has an improved
contrast ratio in comparison with conventional optoelectronic
components comprising adjacent optically active regions 4a and
4b.
FIG. 2 shows an optoelectronic component 12 in accordance with a
further configuration of the invention. The optoelectronic
component 12 is constructed in a manner similar to the
optoelectronic component 1 in accordance with FIG. 1. In
particular, it likewise has a carrier element 2, on which are
arranged two adjacent elements 3a and 3b each comprising an
optically active region 4a and 4b.
In contrast to the optoelectronic component 1, a protective layer 5
is applied over the whole area onto the optoelectronic component 12
in accordance with FIG. 2. By way of example, the protective layer
5 consists of an initially clear polymer material that is spun onto
the carrier element 2 in the region of the elements 3a and 3b.
The protective layer 5 of the optoelectronic component 12 has a
first region 5a, two second regions 5b and also two third regions
5c. The first region 5a and also the two second regions 5b, which
are arranged in the left-hand and right-hand part, respectively, of
the elements 3a and 3b, are colored by the introduction of first
foreign substances. In particular, as a result of the introduction
of dye particles, they can be made wholly or at least predominantly
opaque to light having a wavelength of the electromagnetic
radiation 10 emitted by the optically active regions 4a and 4b.
By way of example, screen printing or diffusion methods are
suitable for applying or introducing the foreign substances,
wherein regions of the protective layer 5 that are not to be
colored are covered by means of suitable masks. Instead of
introducing foreign substances, it is also possible to employ
photolithographic methods in which regions of the protective layer
5 are exposed by means of suitable masks and are changed in color
by means of a subsequent development process.
In the exemplary embodiment illustrated in FIG. 2, the depression
11 between the first element 3a and the second element 3b is
completely filled by the colored polymer material of the first
region 5a of the protective layer 5. Consequently, spurious
luminescence of the adjacent elements 3a and 3b is prevented to the
greatest possible extent, preferably completely.
The third regions 5c of the protective layer 5 are arranged on the
front-side surface of the elements 3a and 3b, through which the
electromagnetic radiation of the optically active regions 4a and 4b
is intended to emerge. In accordance with one configuration, the
material of the protective layer 5 is consolidated in the third
regions 5c, and in this case it retains its transparent property.
The third regions 5c of the protective layer 5 therefore serve as a
protective layer for the sensitive elements 3a and 3b and permit
the electromagnetic radiation 10 to emerge substantially in an
unimpeded fashion.
In accordance with one advantageous configuration, the third
regions 5c furthermore serve as photoluminescent conversion
elements 13. By way of example, a polymer layer can be converted
into a conversion element 13 by the introduction of organic or
inorganic phosphor. In this case, the conversion element 13 in
accordance with FIG. 2 absorbs part of the electromagnetic
radiation 10 having a first wavelength from the optically active
regions 4a and 4b and emits electromagnetic radiation having a
different wavelength.
By way of example, the optically active regions 4a and 4b can emit
light having a comparatively short wavelength, for example blue
light, which is converted by the conversion elements 13 at least
partly into light having a longer wavelength, for example yellow or
green and red light. Through the superimposition of electromagnetic
radiation having a short wavelength and having a longer wavelength,
the impression of a mixed-colored, for example white, luminous
element arises for an observer of the optoelectronic component 12.
In this way, the optoelectronic component 12 can be adapted to a
predefined requirement profile.
Instead of the conversion elements 13 being produced by the
introduction of phoshor as in FIG. 2, it is also possible, of
course, to arrange separate conversion platelets on an
optoelectronic component.
FIG. 3 shows a further configuration of an optoelectronic component
14. The optoelectronic component 14 comprises a carrier element 2,
on which two elements 3a and 3b each having an optically active
region 4a and 4b, respectively, are arranged in an adjacent
fashion. The elements 3a and 3b are arranged on electrically
conductive contact areas 8a and 8b, respectively, which connect the
optically active region 4a and 4b, respectively, to a first
electrical voltage potential. The adjacent elements 3a and 3b are
arranged onto the carrier element 2 in such a way that a gap in the
form of a depression 11 remains between them.
An electrically insulating protective layer 5 is arranged over the
two elements 3a and 3b, which protective layer, in the exemplary
embodiment, consists of respectively two lateral regions 5b and a
cover region 5c at the surface of the optically active regions 4a
and 4b. The electrically insulating protective layer 5 protects the
elements 3a and 3b from mechanical and electrical disturbances. In
particular, it insulates the element 3a and the element 3b from an
electrically conductive connection layer 6, which connects the
optically active regions 4a and 4b, respectively, to a second
electrical voltage potential.
In the exemplary embodiment, the optoelectronic component 14 is a
surface emitter, which, in the arrangement illustrated in FIG. 3,
emits electromagnetic radiation 10, for example light in the
visible range, upward, that is to say substantially perpendicularly
away from the carrier element 2. The electrically insulating
protective layer consists, for example, of a transparent polymer
foil which transmits the electromagnetic radiation 10 predominantly
in an unimpeded fashion.
In order to avoid spurious luminescence of the optically active
regions 4a and 4b arranged in an adjacent fashion, the electrically
insulating protective layer 5 was interrupted in an intermediate
region 5a between the two elements 3a and 3b. An unintended optical
waveguide function of the electrically insulating protective layer
5 from the first optically active region 4a to the second optically
active region 4b, or vice versa, is thus avoided. By way of
example, an interruption 15 can be produced by severing a polymer
foil in the region of the depression 11. For this purpose, laser
cutting methods are suitable, for example, in which ultrashort,
high-energy laser pulses are used for locally eliminating the
protective layer 5.
In order to suppress spurious luminescence even further, in
accordance with the configuration illustrated, in the region of the
interruption 15, additional galvanic mirror layers 16 are arranged
on the insulating protective layer 5. The mirror layers 16 reflect
electromagnetic radiation 10 emitted laterally by the first and
second optically active regions 4a and 4b back in the direction of
the source and thus prevent spurious luminescence.
The galvanic mirror layer 16 can be applied together with the
electrically conductive connection layer 6, for example. In this
case, the galvanic mirror layer 16 can be applied before or after
interruption of the insulating protective layer 5. If the galvanic
mirror layer 16 is applied beforehand, it should preferably be made
so thin or flexible that, after interruption of the protective
layer 5 has been effected, said mirror layer can be folded down
together with said protective layer along the side areas of the
elements 3a and 3b. The metals and metal alloys usually used in a
galvanic production step generally have the flexibility required
for this purpose. If appropriate, the protective layer 5 and/or the
mirror layer 16 can be locally heated in the region of the bends in
order to facilitate flexure.
FIG. 4 shows a further configuration of an optoelectronic component
17. The optoelectronic component 17 once again comprises a carrier
element 2 with two elements 3a and 3b arranged thereon in an
adjacent fashion and each having an optically active region 4a and
4b, respectively. The elements 3a and 3b arranged in an adjacent
fashion are in each case arranged on an assigned contact area 8a
and 8b, respectively, of the carrier element 2 and emit
electromagnetic radiation 10 in a direction that is substantially
perpendicular to the surface of the carrier element 2.
In order to prevent undesired spurious luminescence of the
optically active regions 4a and 4b in the optoelectronic component
17, a first copper pillar 18a is arranged in an interspace between
the elements 3a and 3b on the carrier element 2. The copper pillar
18a can be deposited on the carrier element 2 by means of a
galvanic process, for example.
The arrangement in accordance with FIG. 4 furthermore contains two
further copper pillars 18b and 18c, which serve for supplying the
optically active regions 4a and 4b, respectively, with an operating
current. For this purpose, an electrically conductive connection
layer 6 is arranged on an electrically insulating protective layer
5 arranged over the elements 3a and 3b arranged in an adjacent
fashion. It goes without saying that the first copper pillar 18a
can also perform the function of one or both of the copper pillars
18b and 18c.
The electrically insulating protective layer 5 is interrupted by
the first copper pillar 18a in the region thereof. This prevents
waveguiding within the electrically insulating protective layer 5
and hence spurious luminescence of the optically active regions 4a
and 4b. At the same time, the copper pillar 18a also acts as a
reflecting element and thus prevents a direct optical coupling of
the elements 3a and 3b arranged in an adjacent fashion. In order to
improve the mechanical stability, the remaining cavity between the
carrier element 2 and the protective layer 5 can be filled with a
filling material.
In the exemplary embodiment illustrated in FIG. 4, the electrically
insulating protective layer 5 can be applied to the optoelectronic
component 17 by rolling lamination, for example. This results in
simpler production by comparison with other production methods such
as, for example, the so-called vacuum laminating technique. At the
same time, the thickness of the electrically insulating protective
layer 5 can be reduced, for example to a foil thickness of only
approximately 20 .mu.m. This has the advantage, inter alia, that
the transmittance of the protective layer 5 is increased and the
material costs of the latter are reduced.
FIG. 5 shows a flowchart of a method 30 for producing an
optoelectronic component.
In a first step 31, a carrier element 2 is provided. By way of
example, a circuit board with connection contacts 7a and 7b and
contact areas 8a and 8b arranged on said printed circuit board can
be provided. As an alternative, it is also possible to provide a
ceramic or other carrier element which serves for mechanical
fixing, for electrical connection and/or for cooling of elements 3a
and 3b to be arranged thereon.
In a second step 32, at least two elements 3a and 3b each having an
optically active region 4a and 4b are arranged on the carrier
element 2. It is also possible for the elements 3a and 3b to be
grown epitaxially directly on the carrier element 2.
In accordance with one configuration of the invention, the elements
3a and 3b are connected to one another at least in one layer. By
way of example, a layer of a semiconductor layer stack having only
a low conductivity in a horizontal direction can be used for
mechanically connecting the adjacent elements 3a and 3b. As an
alternative, the elements 3a and 3b are arranged separately from
one another on the carrier element 2.
In one preferred configuration, the elements 3a and 3b are arranged
on contact areas 8a and 8b, respectively, and, at the same time as
the mechanical connection, are also electrically connected to the
carrier element 2. By way of example, elements 3a and 3b can be
electrically and mechanically connected by a solder material in the
region of contact areas 8a and 8b, respectively.
In accordance with a further advantageous configuration, a
plurality of elements 3 are arranged on the carrier element 2. By
way of example, two rows arranged one above the other with a
plurality of elements 3a and 3b can be arranged on a common carrier
element, wherein all the elements of a first row serve for
providing a low-beam light and all the elements 3b of the second
row serve for providing a high-beam light.
In a step 33, a protective layer 5 is applied on the carrier
element 2, in particular in the region of the elements 3a and 3b.
In this case, the protective layer 5 can be adhesively bonded or
laminated onto the elements 3a and 3b for example in the form of a
polymer foil. As an alternative, it is also possible for a liquid
material, for example a clear polymer material, to be spun onto the
carrier element 2.
In accordance with one configuration, the protective layer 5 is
opaque to electromagnetic radiation 10 from the optically active
regions 4a and 4b at least in a first region 5a. In accordance with
an alternative configuration, the applied protective layer 5 is
initially transmissive, but is made at least partly opaque to
electromagnetic radiation 10 in the first region 5a. By way of
example, the introduction of foreign substances into the first
region 5a is suitable for this purpose. As an alternative, the
protective layer 5 can also be severed before or after application
in the first region 5a.
If the protective layer 5 covers the entire surface of the elements
3a and 3b and is opaque to electromagnetic radiation 10 from the
optically active regions 4a and 4b, one or a plurality of
transmission windows, for example in the form of cutouts, have to
be introduced into the protective layer 5. This is carried out as
an optionally illustrated step 34 in FIG. 5. The production of
cutouts 9, in the case of a light-opaque polymer foil, can be
carried out as early as before the foil is applied to the elements
3a and 3b. In the case of a spun-on protective layer 5, parts of
the protective layer 5 can be removed in third regions 5c or be
made transparent to electromagnetic radiation 10 by means of
suitable processing. Methods for structured shaping, pressing or
casting of the protective layer 5, for example by means of a
so-called Boschmann process, are also suitable for this purpose.
Further cutouts in the protective layer 5 can be provided for
making electrical contact with the elements 3 from the top
side.
As an alternative to the introduction of foreign substances, a
protective layer 5 composed of a photosensitive material, for
example a silicone material, can be colored in the first, second
and/or third region 5a, 5b and/or 5c. Photolithographic methods can
be used for this purpose, which lead to either coloration or
decolorization of selected regions of the protective layer 5 by
means of exposure. As an alternative, it is also possible for
individual regions of a photosensitive layer to be exposed and
fixed and for unfixed layers to be removed in a later development
step.
In an alternative method step 35, the electrically insulating
protective layer is interrupted in the first region 5a. The
interruption of the electrically insulating protective layer 5 can
be effected for example by laser separating methods or else
mechanical cutting methods, and severing can be carried out before
or after the arrangement of the protective layer on the at least
two elements 3 arranged in an adjacent fashion. Previous separation
has the advantage that it is no longer necessary to carry out any
further method steps after arranging the protective layer 5 on the
elements 3 and the risk of contamination or damage of the optically
active regions 4 is thus reduced. Subsequent severing of the
protective layer 5 has the advantage that the interruption 15 can
be carried out relative to the elements 3 arranged in an adjacent
fashion at the desired location and in the same production
process.
In a further alternative or additional method step 36, a reflecting
element is at least partly arranged in an interspace between the
elements 3 arranged in an adjacent fashion. By way of example, a
metal layer can be deposited galvanically on the electrically
insulating protective layer 5 before or after interruption of the
protective layer 5. As an alternative, it is also possible to
introduce a reflecting element in an interspace, for example by
depositing a copper pillar 18a in a region of a depression 11
between the elements 3a and 3b.
In a further optional step 37, a connection layer 6 is applied to
second regions 5b of the protective layer 5. Applying the
connection layer 6 makes it possible to make contact with the
elements 3a, 3b and hence the optically active regions 4a and 4b
contained therein from the top side. Furthermore, the connection
layer 6 acts as an additional diaphragm element of the optically
active regions 4.
It is pointed out that the sequence of work steps illustrated in
FIG. 5 is merely by way of example and can be adapted with regard
to the order thereof. By way of example, it is possible for a
protective layer 5 firstly to be applied to the elements 3a and 3b
before the latter are arranged on the carrier element 2.
Furthermore, it is obvious to a person skilled in the art that all
the features illustrated in FIGS. 1A and 1B and also FIGS. 2 to 4
can be combined with one another in virtually any desired
manner.
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